SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4043aac8f195c9f016df6ca902028c63be18fc50973701872e02fd981cc37a87' 
  AND token = 'RFfENzgaHVshqg6ZaIehfDtQrgLHReCz86EunAc1HUA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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