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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec5126a097f053cfb48d441f536d0e28ee8bbf3af8d218ec7c65f3d13af28b1e' 
  AND token = '7+zJahUrc/QbNqqlgkRQX+Q+Dtr/kpSdQlVjL7fOhuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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