SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '429e76b3fe9a021c542002d4b6c6247b8b30bb7ab80d306525b4f4496cd89afb' 
  AND token = 'PhEfK37ydrafYzm/0zMVoDIQD/+0qpQyxkcluWg5HvI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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