SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6991df01aca1fb39eaf07a1b158cfd6928ff6ced1994875d9243ac460bc0fba7' 
  AND token = 'UvmiFAjRY8Xuz2Xvn7s1VSDm/elLPVjNcwFnP4rBlII=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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