SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c736891be5212cfef7bf0e7c8d7a0f2a7b16821159267d6feca746f5dbca4dda' 
  AND token = 'qV+A5JMcI6IBZfhYCrayqUgKzdnmMhpEt0XVW3fwRqo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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