SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ba749e037c6edcb23400e36237911d56ca292502727766471b15179e59e5e9ae' 
  AND token = 'eO0W8JzceIAQnLKq0tELmDwWoT6gaMZHo3BdKBtyZi8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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