SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b53c42a78c43cae170c5404910a03eb865d79d7773fe3d44f92f51f1402b33c' 
  AND token = '71aHsFxJPyKcWM3tCFujbl9c9GO7ndKcItnrw+ZPCbc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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