SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c96211517e3bfa2da93274e24592ee3641d6d1c95254df1d249272319128fc28' 
  AND token = 'twuTHfZmZWxOOArQG7+s8IqUDicrvre4lNTkoBOYwrk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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