SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '814e0be259dd5f4324001fb6b79e964461993f001e236c9ccd4317545b5ba327' 
  AND token = 'hgJBePQVQ+nvh26tBrNWYEMXSVmbsFZiY9PBxgIcteg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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