SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9be91a90ca39867b0f26d89ab47d980e45ab05dd017c8bc691e4016f66d6374' 
  AND token = '9b/w1msqYyp+pzJGJH1FW2LXPIKOWXoymg+06yIVzaM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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