SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e12d8075075fa212bd78e252afbc9b58ceff8ec01845c8134a6a208696371692' 
  AND token = 'Sj/CZRVzP+EpM64WPIH//4UNLfXEgf92hSp4DwrFSts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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