SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '543877b27cce4f9fd6fe39301b9fbdcee5793007aec1db65f91a50cb55c57768' 
  AND token = '4N8Yovw24yFKSXuB4REAj2fcZ1GsSY5+hoDMlwhPmhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}