SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a433f615b8ee260aaf3ae632a66d8f2e66f462fc067151d139cc518a7173661b' 
  AND token = 'ut7xYkbeHcb9Q1ZSzFfGgdYHGko+RbH0MFw2+PmjCzQ=' 
  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"
    }
  }
}