SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '236134d79aa68aa61c2d182b3eb4f98b277512029cd46c518be7a43743a27a4d' 
  AND token = 'URFMDctsq3V/XEXlO95EutmfxUUld8D7Tg50JBLJC3s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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