SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8bd6ab3da61f88ef305304869923f7a5108733a97f8cdec7972026eaa74278f' 
  AND token = '6B7niI+hVUQmXZRGnmzmZEImhht7fwtDVgD5Z4hnncc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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