SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '285b7992a8e6c7b3e6dd44b6dbb7835fed9a4b3cf181d84f7ed307fa50503657' 
  AND token = 'NmFVA1ZzuVHzpugvWXggxFMFQKxRIqdEOElxYQOEnrU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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