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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0c103c1b45d90ef42a06d37a25d5d85dfdfab75b5ef697a6b34f23fc0288fc8' 
  AND token = 'U4AKPi8mf4BjzqVnnv+f/3pvCBfvcQ2TPLv2Zr5fX9o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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