SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a90c625e953e57e2eda32b4dee814062133abbea4665a165fcd149ec4f837bd9' 
  AND token = '6l7TW+OuCd9SQU9CRr87CqCtF9uA3Dn9UWJno8E3ShE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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