SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8ac9a1479087cba40ff93382b96fc784c04874c506180d94105842d8ec64631' 
  AND token = 'CcqpbLvTJ7G5+4o1ZLGEFjmtikUxWI0Wwwhoq2ix9gM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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