SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6f812a38799a3927ec54e8bd010af45d4605b1ef398b0b569a65b47b50f7ebd' 
  AND token = 'ug1vk8bALw/jxUtECjntp6BYpGOJrB3TB+MmYJrA7eA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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