SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dccc6f391db2e3d26bfa0937cce5fd977757a68967065bc9a46dda41bf93236f' 
  AND token = 'l7RZs3JT5wmhAURlXsRsu++v5mDpq17xSnYuSLxCrkY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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