SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c529c807198b82f3eaf65d83446ebf2fd90d5987bb14aaeb1edd7934c99f0f18' 
  AND token = 'd8UcCONisqwy+6ozhpixzvMX6sjhI3Yj0zJ1UN2AmL8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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