SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c42db5eaad31a5f12b4d78c3124f98d4c6029399c511e1fc77b46f5cb1d29d7e' 
  AND token = 'eTxiAUamdpIrv5sJMhWYtMzsbaUT8kSjbycqM2K3bCo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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