SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81b28894fb33e22e06d77b81c5cbed3554ca1047e3197aa271bfb6c6358baca3' 
  AND token = 'CjvJ1ktNLCECjPcVk7zOuwat/GCiTHls4dG4I/SoKmM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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