SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b44a8b9df00a0397b10de0c8961b2877f4942eebf1151ea4fceeed24d759044d' 
  AND token = 'bZ5tTxqUwPOPhUz8QVvyo4zASgxMd/jyXmnCxQh88mM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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