SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9721c6b6493ea9f01636de91b012f707d69088750fca3150301ac08442a98acd' 
  AND token = 'tVTbwN0U2eDRAxAcTIQBFU4zOM2BdEapei0FBvwukiI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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