SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ec786ff6f36e2287965c422d3097edee32b39588d429799576388571301dc5c' 
  AND token = 'kphFJbb8w60HcrWa229LaCrK/3ETMyRQfwdfSfXhcCo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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