SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec1c29f8f334a6200aa1b492f83a687462691128e519a0a2bb6db35283363c7a' 
  AND token = 'HJUYWDJpJvY/gSR3Wij/swYgPzYaJq7S7y90DT9BS5g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00065

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}