SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42acce4701d2024d72ad879b193c0cbeefcaa144d4e6ce606d535271945a5b23' 
  AND token = '78YbT37WUOFjtJrS5dg1PczkIhYjN144PhyBSOKksxg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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