SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e655ecfece460679c68429e7fae723e3333f30829f68181d96b791bed471431a' 
  AND token = '//tOZ/UWEHq62InqwHZA8uHGOCMo+lPsQOsBYN+BMPs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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