SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '204e21bc859c91984f809fa3ecb7eb84df257f7816b38d697f3988a619a5acde' 
  AND token = 'NfZ6fqe2hC+0cRH6mrEfS8WvePyZid8uYIUyTwuABiQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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