SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a34e8ec356804e5f8d6be83e3abad0a5f2d2ff8252cf51f2eed8aed61d488221' 
  AND token = 'qTqC9NtuVAYF5CRNuYJhJ+ZgHNAYNg0vob5hPBKVpWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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