SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8309252ddda5107a55f736f6f9da489686051abd914ad0085c9a11a34d144756' 
  AND token = 'Zx9XvQJHzO6dWBz4mkwM7mrqq7dNUnhfqvQVLi6jXXY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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