SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ce936554d5f860b689c428aac7b501c88b4ebe14f01028588b8e7ee896a914c' 
  AND token = 'cMgBDQTVWAnjrJ9/qDEoDY9P/u+ALSI1MuUTetVS60o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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