SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'abdfa9376c1992aabdb47e5577b0ee08f8e6d360edc943096ed576c9e545473b' 
  AND token = 'rByyx9MlQIdaubFk3DWLHF8UueWNrRNP5vt4LLt97Mo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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