SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '571635380bf3fe2d7a81f1c007ac952d9088b58ad49c909d35fbed5b19224a90' 
  AND token = 'VekE73ZxtOQlfEt3QtxYwxoI+HTGozn3AuNMbG/IESY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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