SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52dd361484458c553ae7f9e0e3b841d7910dac574264911ca25efae0ec7c1c21' 
  AND token = 'xnGtKjekqLKRF9SLhgyrMErj9n+ZBSCpaYnkVVV7vMs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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