SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68aa8039f277bcfde3ef7af7431a91a8bdd72fc853513c4661a1053fc2704e68' 
  AND token = '6qkW47XUKW+YO1GNca4P6q4xPBUvyR/Im08HFj3o+0Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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