SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c275bfae75a0aaf6faa53a5f4122031fb784bb6ebd1c2eda1e85e556696401bf' 
  AND token = 'oE3oUMwJbo9/T7o0RGLZTokHBiethwOm+PWT0ZxYiUk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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