SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a463e932b5864fdd022f401d7d7a7e0ca0eaa90b109d82a0da356864997beb6' 
  AND token = 'NESqwXvFlloML1AozMtE0pMxIndX8psYny9dOoh6RLk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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