SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d66b561ce45696a00b70ba8bbdbef703c035c5ff9063634d8906436ca994f89' 
  AND token = 'wjKSV2gvWlfR5JVDkCKEmJDVzeFmGJFBd+xWdQW8CeY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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