SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff8ad0ec996defb535b66f277254a13d723cff12426091b4a1563ed40d7d8f24' 
  AND token = 'm8xPYQOua+k6UpRg966CbjYzxPj8fQbKIhOm6z6ujZk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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