SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0f3f8455e652871674698182e0365b86ebc69e258b9d6cccb42d88f0e9913597' 
  AND token = 'EvPe2d0aTNbG9x16Ra4VSgm0CpCmdPNUjGsSuBVCk3Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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