SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df851d805d8807197c346f61499e702bbe1566b23cce00da48f95638eee7b68f' 
  AND token = 'vkVovLTNjCjWOA5R1u/BKTP9koVDjS9FLGHJch6Cgyo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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