SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da28d5524775db64abb600d1b9382a5670cbaddfd1516c86162af1bf71a6328c' 
  AND token = 'thBLq7F5pHFtfJFMMVpFGeeN8aSBCSbw8Pl2Gezubms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}