SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1e6fd3e70da2d84beebf22026075f0458c84655fb93245208e77288a6596b0fe' 
  AND token = 'oLo+5wjxTmTkOdMK7bBmuMg1UfdVtzNkLnmVHLuClM8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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