SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1993ebc2c53ff36e89feb59d966c3e926cfcefb06717496578516b39d1b0f9a7' 
  AND token = 'PnPS2I/COuXS2/0grJ0oE4Lny7ptZYbbPoxWGVmKuxw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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