SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90d8dc40844d2b301aba156585bcf8f23ad89f90364c2f0457960ca7ce880899' 
  AND token = 'fE8lBDUiu4TfYYpz71AkBc1belPvdxPyI7LDNN1KfI4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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