SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b027e633ffc7922852898fe19be306d1b2eac53e3e2900cbb48f0e8c71c1548' 
  AND token = 'ujPjoVZN6SEb2eyiEOvXVufgmmrL6uEHANCiF6mQAKo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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