SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e16b1cf2252675481d34fbe5501fd5d56bf85e8455279e396e8982284fd18b53' 
  AND token = 'zlsBYM7lHw1PzYH8KQFBvMmWBu/25jlfNYnzOPQJigo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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