SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd66bcb1301a4295a6d9242149943ad8ffc7025f1ba4fc5dc0fa673affce6840c' 
  AND token = 'zMJKNFaPq3RgBHtpoPWKFt9fYtx7BgDZ9le8JPPkVjc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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