SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b6cb043d88d6493543fd10ffd4811245518d908ddce275cde3b42e30b86ff1c' 
  AND token = 'zrDKVI/Yx+FVPhvsLzqwPJfiR9cIFG2/RUnOWHVZjuM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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