SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'debe2149a8fecaac86f7e1372ba52998806896387e1444249d64c386b531e642' 
  AND token = 'k9rAksrO/ACWg/79K6GmjQJpielbVEjVDC+lBmmDuBk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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