SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '310f60b0dff2623b74524d59ff56f8ffe4fbabdd0011d6fd82d052b68746355f' 
  AND token = 'oWe7nVHohMyJiV3QfAbXP1LXeJRaUkDOKv9n/iJgVwo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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