SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12ba983edac3bfacae45973a20e20e1cb52fe04b40215b65f997de9831690dd7' 
  AND token = '8tyIKhf533Fv7sYj9DXytrvzktXHBSuhrhxYwVunIK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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