SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42948d828682564517cbe66d483dde740c3e7159e1d478fea27a197f76ef9378' 
  AND token = '0H7VpqFuK5UhD/UprN68oGwTisl+D7uXAh1upMBdHxU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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