SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb1ce0a29195b4d53fed8a3fdf49e70b0a81c1df2d37e205766a362f4c3b8ced' 
  AND token = 'E/CLTBIp3/CMmHupDfedyG+zQHWyZqWp6jGH75gPqvA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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