SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4684c2495df1dbcac570a5697fae65c48dc09c9e1b18e8347aa118fe69774470' 
  AND token = 'rHDdEkZnShrjGtQ1mTmAm8Au16dci1t5HLhiPNPZlg4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}