SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e9185901c695aae6e0ca89ec51591cac8e616ebd0cb6a7ed517daae99a9a863' 
  AND token = '9QmpsfIwA9PfAnFBetcJDDXUrvjnAWM8Ee/eiSJbdDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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