SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90b0c032952759309358ef5c376456db2cbccb9fcc0f1c2d368daaad6936a3d2' 
  AND token = 'vDjma7tU5lNGS4GlH8r5zRnKY5kZhEZCVZMVUmpgWJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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