SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c57515e2af6efc214d8d5a626ad362004d86f278be283511eee2b47dd6527e2c' 
  AND token = 'nXHejnKuftOaIsQk5zlf/H2pbWar3tLKESWSIquCkZ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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