SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d3db9a46b7b0b88a5931494ee280a359e857f58318d034978dc3c4c22de5f23' 
  AND token = 'K9yORD/naVVI41+rASKkh31nVvXt+CDC2LG15HUgwE8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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