SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df0a236568183e3c97d77214d2fb529380d42684d73f93faefdc54f91485517e' 
  AND token = 'DhI0IH2rCfMToVwA+CkZsJ4NPzLvdWyQARNgWQls5sw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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