SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38cc13137ad35313a64be311d6b044d0b542db44e79620cf23ce375377b657ab' 
  AND token = 'aPuWa2Nf5jVJZfNRxCCthG+jB//uXotjlZEZPGOXwFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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