SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ef51f2544be97f71cf4306cda978ec79918d7add79971761d7c5232817cf5e6' 
  AND token = 'NEJAmmd0OqSg+tENIyvFBqjnqUO/EriDzSvTXEj9v7k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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