SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a9e43737b2119d51c0125596287e895eb8a831aac139432190fb8efdb3685eb' 
  AND token = 'fM6xqD1O8FFF3zqGmR1tJvxqKj+wMkPoPSzwKCwHVXI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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