SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15a027708cb7b71801ea7caef883f1263d3fbd7721cbf33dc130ffdbee2748f3' 
  AND token = 'YieoZB3rN8QF0j6knGRR+gwOGtNKW9XxiMlhIiQjvkM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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