SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70e77ef86f03b2059bf353e652d06f3578d1f1ee48efa2052f679c703672b221' 
  AND token = '0V8my/hiiiv/TPRSiGqD2VunJAxm53/UxrrMEfZMJtE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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