SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78c7fca6aa573d6f360ac255d79287c3df16d9d541041687c6046744ef7816ad' 
  AND token = 'JjAo88vwGM0xOPSwBzZ7BKEPKlFJR7gScsh3uX1KiCE=' 
  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"
    }
  }
}