SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a84cf8d6e5115580c49748a0a132573d4ff5da1644bfa1231a8edfbe109cf36' 
  AND token = 'QEakW3uZ8mvo5f0ePuK0kukrGjdaOfnynzW3irHxiqI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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