SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78245bc44540895addd267af049f971da404687bc4fa5816135e946e46bea956' 
  AND token = 'BKqGpD/zbJ8cgyspZNLhbc9aHkvbVYshquHvwBKP3BE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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