SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '849e7ff2a4929167c37a2602cab9346169e601c48ca4b700250f8988fb12911e' 
  AND token = 'U7OfHyYVbVXro+IXs9LziQ3svED0L3KjwxrzPjD9vew=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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