SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '607883cf946cba6997a4775438d96e43c78632ffebb0a4bf645e512ef2ab0502' 
  AND token = 'MnQwl4eX6OtJqdcWdzZaqIfxINBY2TUnTeCalk/dw9k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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