SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a272df34e636ce4bddaac45556d0e8347b98ad0bf4f40e478583f6605607754' 
  AND token = 'QTdRUaaQjiSo7cDkG2+w/1ryQeevc9iV5nx6JKyqfWM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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