SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78b2f1fd38bd0b98f10859076b2fffe8136bdcfb84c990932dd3fe241847e848' 
  AND token = '2zvQscnnkQRna/8P5S+d4pyglzuynKlqjJDLg6xhuyI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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