SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17ab4c3d94da2f9fc544f363f020bd1534aacde4ddb765dfcfa5db1db63d0e30' 
  AND token = 'cMYp43mmNCWnbxH0kVXGhBNzD7Bv9ehjWkLvWez6MIs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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