SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db38ff5d6740a1fd281bacd627df5add6d785ec6794984659af2a31f1dde6576' 
  AND token = 'oNTImKHceiaf0OYje7SbtDilWJZ0GFWSfUronmGJVME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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