SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '668a702adf79b40b231bd98462bac9d45ac458880ece280fe97badf154340284' 
  AND token = 'dQwTdpvorkb1x/X4aB2FtD0fP5Ip8uMDQsXGFIzWrmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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