SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b459b02d4989645accf543b6f83f5aadb1068b1996f5da7f927a24530c264cbf' 
  AND token = 'HRB9hAS0OQWPrcmLxqDuNoU9LGLJIL0iz/7CXHxTw+A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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