SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4940698257b66d2fbfb006cfc183e6378688fee33167ab5441fac4734cb61b20' 
  AND token = 'Te3hb/tYnCDPYYbvceK2GvhyDBFAm0QkjPmV/w98PW0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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