SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92bdc2889f62123414abd0f7f975e84390f6cc8d04c1b9fb2471c1b5372c3467' 
  AND token = 'N5flfUOPaDZHyoeWpMw8dgrrVJ+8Hs5dBoyFzFIckdQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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