SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4a82766d56a1a4504fcc5f21174dd209c31ffaa106ba4cb2c33ff9978146ce8' 
  AND token = 'tgGxg0iUlSoUa21mEBUqLjvCWt/8wgYuxpYCat0PDbQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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