SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8bdda0dad59356ea6897ecfa45450433551759d79429cbebec212cd33431924' 
  AND token = '2XWY6VmsCXyRKNVNBq3pADsnEABzp57C+kmro8Js6jA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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