SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1748c5b2d5cfaf49330af303a161618c978474269dc44d53699ff6aef61f5754' 
  AND token = '8xpSiGs64ngegm3qmJoDUqNQHAEvFSg7uSpCgVbv3rY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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