SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '973f6555616673d323ab6ec5ea712adc94f55f11e0aef665c6235d1b20bb9c8c' 
  AND token = 'GPgz/mkTp4KAYTk1mj8SkD6gJedcyoZ9+/JCB3BlYIc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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