SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2f9540e93fbc61aad0ad37ce2a4a478986f72bf21a5b14b6f85c882a03b76ea' 
  AND token = 'PLC7O3aHyrQms41ZeVwTYgQvyztw0cUaB/V+jWOyX8Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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