SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23b8e3b5663da6a018a1c796d2bb990f229d153a655fd4b250eb5a75c3a076f2' 
  AND token = 'PlqUa7OQWGL3MTOd+FFR9gmmGHp4dD1gWRrOcV7kmWI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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