SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '797fa4c3f883870ad589b5054475e01a8906442acc1da8de6141a74c6885b8cc' 
  AND token = 'a0rr8rbeKDuLuvGSL6pcrIC6fJhOyYhWSjND/DL+ntQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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