SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91bfbe81df523fec1aebf9d1523666750b4dadb8df941bf87dcea24bc496af24' 
  AND token = 'hP8D7nrlpRn4Z/T+4WWZgxVd0vQhN/vQuPbN4F+hBD0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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