SELECT 
  1 
FROM 
  q_lock_keys 
WHERE 
  key_id = '4b68d0940e86cef20399ffea1ed3403b57b9d0b29512b252c9620732e8258d91' 
  AND token = 'qfCU3fGj64wkm+0yDK6X4/OkfM6nncLOWLHrJzUZlVs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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