SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5364c4a3aca8af4f7967afb9b252c8f8508d63f14483cb9e148fee20379681ae' 
  AND token = 'VK0vDLriId8GECWfoRZYhZBwRwS6rkTaGeadTf+wVbM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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