SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e242a36fe12d09a025eacad34ae932edf04e8b3ea21a1996318471008e68d90e' 
  AND token = 'iFleNAamtTXAqe3FpFVaBgI0i+cvYj7NYY/rYdvwqiQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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