SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03a829ac3c3353ef4b4c8d983727c2e66afde415e8bc49c95f80dd1407726471' 
  AND token = 'O+JFEgjMgjrOzzc6lS4qZRMZhyrZLqfpzFBQzFRkB50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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