SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '318dcf36a1704d18c1d0474add56f4a89924bd4c9fb0b8fd6fef0eb8e9b75c2d' 
  AND token = '8rmvTiRz8yYubhVxIEXKCga+2keSwDv+GKSL5BWydpU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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