SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '666d06855ed074849b4da8aa12790243c4adb9ac4e123009ab846897b308f9f8' 
  AND token = 'Nd9Y9fQf8i35PRNaQqUAKt84C8PzXFOKgPLdseyCxCs=' 
  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"
    }
  }
}