SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '798f026dcfa706c2fc118226c31d2b71c84a60b9fe762c5f41ae47fd801d2ff8' 
  AND token = 'WT6gKv3KxW+s5hMDjg9ByCR3UaH4wl/uxC7jGlJxkY8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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