SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '46939c796aafb2ed9724d1781bb6f33afaa87a87093a138cbd3fc8c73b71f034' 
  AND token = '1cFakyz5p8AmqaX/BkDd6I+lRg4cN7dm/2gaY57dvoo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00010

JSON explain

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