SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89df1fc964714498698c642871fd1dc879c821c9cbb28430b83939e9afd8fb42' 
  AND token = 'GwNqJwdbYIzAvMYmegBy6DzlC6btzL7f5l9p/Rmt+nc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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