SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc941d42b099089ab5a7eb05fcf77c7f5fd02e6c12dfdce2d9b817eed292056f' 
  AND token = 'Ec4LaX/GxtkrGpxILE9IrkiYzg7eGzRSqFuLYFi9CNM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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