SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35090eb58c905d065d5510efdb793d12ba552b4f81e4c9eb2df7a2874eb0c058' 
  AND token = '6vkADqIFvJN2F8GgMP/SSlE3dtEDxQ+jcGx0SLK604U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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