SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7788d0a505efd58bc5d3629f5466d5d637a008d90118f4db8d0e36805a0c264' 
  AND token = 'DGsYK89AbuC3Dti2mQ/zHBipzc0kWXd36Z0jcjD7r/Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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