SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c18f6494275cfce1c9716e545377ebab04ca3c6d0df21606d8daf6d3a1a3772' 
  AND token = 'MBRKBEyxcn/qsh+9bOMgR253SA3V6FBJ6Z4oTzhIyGE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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