SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd03ce0a9d90d608024391312cfb1ceb0ced87fe46e42b573b5ad3f1759deb594' 
  AND token = 'sHpy+bmtquPQT2f8tAb156fqBpaaf7KHG0rApdQ2ZaI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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