SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd55be3ea5f04449ddce88d8b2279b7cf929a206b768579c16067db6c163c1644' 
  AND token = 'MwBKMJw9vF7MWzhafWwPzlRbKW8KKuSGiIyomlaLkqY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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