SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c385346d0064ceee99c64fdfe88780cb7bde7629707550104d9ae6b86205d08' 
  AND token = 'lwkWKT3B0PNlGEgywqCBQwPKydj+NJVOGo9QYj4caH8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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