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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd84f9a0656c34bb96bb408a97999f3980a76e3df68de8fb3995d513f2af0421c' 
  AND token = 's4YiatHdkzB3rFGKLZiI5v2zhyUsyzFieX501G273gk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}