SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be795fb5585cbf2b46a99b5a9657f343cd29ab4113dfa18be708276ced1a6225' 
  AND token = 'phUSVzgkJbrsqmgem+6zXOhypha7uPZt8Ehjv3SE2zk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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