SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec14cd5b78fd7496e836e337cd0774b94304241b757097f55d7feaaf92bbec30' 
  AND token = 'BMqgt0kglba1+Y8t2LOrNCqTg+/djPffSTtwISmePlQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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