SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3b2b32ba8213f1797685cb7b95601396840491256f7b2c3d020786fbcbebe51' 
  AND token = 'zX4xW+7/uKsPHzJAHdN7XJKLHy24j+/3VAUtG/6xRuc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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