SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20e0a228b1fc73326a0da7cba74d44860b6d56b5cfda4e0641ae68276ef536ca' 
  AND token = '4DjmzUQucpumhan4k5HmYIYM3peYHAUFsfBfrloGB+4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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