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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2edf6b45649b2d915cdf7ae8a4f4b97f3cc8908f34667e0d9a975ecc1748c1b' 
  AND token = '4ZhpTmFFFfdxr7MDobsTLPUPSS7ScmqsvzvpoyOLwz8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}