SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3dc9c3e04713f17928739bf6afdea70378b0cbde490538c0682058dbcd3cb782' 
  AND token = '6hpRy5WO3cwEWPTU4NZoRzxvvk+KuSxnBbC+o/PoS84=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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