SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '810df6ca89b939f1ba09328a9a1afab38d1c989731e84ac017fda20c225f811c' 
  AND token = '5e6OJVwJLK2NYJCQ3zHqE1hmQ7Di2QJl6+6iPXbSRDE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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