SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e041fcff93806905a5917a9162063827736768070c7efaa1ba01d17c2bbcc25f' 
  AND token = '9r6gqCGk+ikMy0om8zhRtC0qWkjvC6uEuXjxzBXuj1Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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