SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '728f4b2f5d521d57d796b7c34aa5b96b9d96dd2fa02307f4d97812ba66bddb86' 
  AND token = 'zDkdIi+aleonWbfvr06DQ3KwCZFB5ZjzV8qWnSgLSkg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}