SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9878e35a9241de2b3374d508a8bf3f8301db9159643494e40b13c39615e6aff' 
  AND token = 'B4IJ6MufV//iLv43PAT9oqZw+cNHVrvjRFhrJqIc79E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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