SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c97dad799b71bfa8a09ac6593f5ff1d22f021d14e2101ef0d38d007f2b8e2a54' 
  AND token = 'qj/lu+UPrxR58rXHOa5IXot6SEsyD6trjnY/+98dDz0=' 
  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"
    }
  }
}