SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5636cd9161166f7b75468bf6616ba5340c8352ce4bf76b5ea11a686e735d79d8' 
  AND token = 'mY7OXIsMV8fgUlWvyEC+rYnN+5AOSNQJI2Nk1LH7bpY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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