SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68eb564e1bfcd994658c53c61ea48d8f8f8f8ddcc148fd529a6fa5ab80fb0594' 
  AND token = 'LhFRuZuapjnJHZ0YWSx6mqixB7NxbYd37YU7bKnf6/c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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