SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2abf641ccb49fa1f18fe153abcfd24802c921f4a2ffde53314134b42b8e05a85' 
  AND token = 'UW32tTRWF+VbVLiVcvZmuWkCkt50+ftreLuYeuCDUIg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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