SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2eb52049015875c38b2e42e9e5444b7a5b83ede9f9cf643748475f54ab037c50' 
  AND token = 'DZCGtqp8Sew8UCKaHVBdTcBMmJb/tXYl/71j327zLyk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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